Factors affecting the parasitism rate and the number and sex ratio of offspring of Asecodes hispinarum Bouček (Hymenoptera: Eulophidae), a biological control agent of Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae)

Abstract

To optimise the production of Asecodes hispinarum Bouček (Hymenoptera: Eulophidae), a parasitoid of coconut leaf beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), some of the factors affecting rates of parasitism, number of offspring produced per host and sex ratio of A. hispinarum were investigated. The numbers and sex ratio of A. hispinarum offspring per host reduced significantly at extreme low humidity (30% relative humidity [RH]), but there was no significant effect on parasitism. Photoperiod had no significant effects on any of the life traits tested. A. hispinarum was able to reproduce via arrhenotoky, and while increasing the proportion of female parents increased the number of parasitoids produced, the proportion of female offspring decreased. Older females showed a lower rate of parasitism than young females, however, maternal age did not affect the number or the sex ratio of offspring. Increasing the number of hosts offered to a pair of parasitoids significantly increased the number of parasitised hosts but decreased the parasitism rate while the sex ratio of progeny was not affected. Present work showed that to maximise the production of female parasitoids, a parasitoid/host ratio of 1:1, using one-day old A. hispinarum at a female/male ratio of 3:1 and RH of at least 55% is recommended.

Keywords:

• Asecodes hispinarum Bouček
• Brontispa longissima (Gestro)
• mass-reared parasitoids
• quality control
• biotic factors
• abiotic factors

Acknowledgements

We sincerely thank D. Warren Conaty (CSIRO Plant Industry, Australia) for editing the language.

Funding

This study was supported by the National Natural Science Foundation of China [Grant number 31101496]; Special Fund for Agro-scientific Research in the Public Interest [Grant number 200903026-5]; National Program on Key Basic Research Project of China [Grant number 2009CB119206]; Key Program for International S&T Cooperation Projects of China [Grant number 2011DFB30040]; Foundation for Returned Scholars of Ministry of Human Resources and Social Security, PRC (Year 2011); and Natural Science Foundation of Hainan Province [312036, ZDXM20120026].

Additional information

Funding

Funding: This study was supported by the National Natural Science Foundation of China [Grant number 31101496]; Special Fund for Agro-scientific Research in the Public Interest [Grant number 200903026-5]; National Program on Key Basic Research Project of China [Grant number 2009CB119206]; Key Program for International S&T Cooperation Projects of China [Grant number 2011DFB30040]; Foundation for Returned Scholars of Ministry of Human Resources and Social Security, PRC (Year 2011); and Natural Science Foundation of Hainan Province [312036, ZDXM20120026].